Hypodermic injection device with shock absorbing spring

ABSTRACT

A hypodermic injection device is provided comprising a cylindrical holder closed at one end and slidably carrying an ampoule with attached cannula facing the closed end of the holder, medicament is provided in the ampoule between the cannula and the piston in the ampoule, a gun spring assembly is associated with the holder and in operative association with the ampoule to force the ampoule and attached cannula forward thus driving the cannula out of the closed end of the holder and into the locus of injection, and a counterbalancing spring is positioned in the holder between the closed end thereof and the cannula end of the ampoule to counteract the gun spring force.

United States Patent 11 1 1111 3,797,489

Sarnoff Mar. 19, 1974 HYPODERMIC INJECTION DEVICE WITH 3,403,679 10/1968Sinclair et al. 128/218 F SHOCK ABSORBING SPRING FOREIGN PATENTS 0RAPPLICATIONS [75] Inventor: Stanley J. Sarnoff, Bethesda, Md. 641,6266/1962 ltaly .1 128/218 F [73] Assigneez illligvlval Technology, Inc.,Bethesda, Primary Examiner-Richard A. Gaudet Assistant Examiner.l. C.McGowan [22] Filed: Feb. 10, 1972 Attorney, Agent, or Firm-Witherspoonand Lane 21 l. N 25,123 1 App 0 2 57 ABSTRACT A hypodermic injectiondevice is provided comprising [52] US. CL, 128/218 F, 128/218 D acylindrical holder closed at one d nd slidably car- 3193 2 tying 'anampoule with attached cannula facing the closed end of the holder,medicament is provided in 128/218 218 218 A the ampoule between thecannula and the piston in the ampoule, a gun spring assembly isassociated with [56] References cued the holder and in operativeassociation with the am- UNITED STATES PATENTS poule to force theampoule and attached cannula for- 2,752,918 7/1956 Uytenbogaart 128/218F ward thus driving the cannula out of the closed end of 2.8 92 0/1958 Rkwell 128/218 F the holder and into the locus of injection, and a coun-3046985 7/1962 521E112 1223/?18 D terbalancing spring is positioned inthe holder between 218661458 12/1958 128/218 F the closed end thereofand the cannula end of the am- 3,605,744 9/1971 Dwyer l28/218F l t tt f2.701.566 2/1955 Krug 128/218F poueto mun erac hegunspnng Orce 3,314,4284/1967 Johnson et a]. 128/218 R' 6 Claims, 3 Drawing Figures HYPODERMICINJECTION DEVICE WITH SHOCK ABSORBING SPRING SUMMARY OF THE INVENTIONThis invention relates to a hypodermic injection device and moreparticularly to a gun type device wherein spring power drives theampoule and cannula to insert the cannula and then inject themedicament, additional spring means are provided to counteract saidspring power to provide shock absorbing, better dispersion of medicamentand safety with regard to insertion of the cannula.

In the device of this invention, the ampoule and attached cannula areslidably carried in a cylindrical holder which is closed at the endhousing the cannula. A helical spring is positioned around the cannulaand abuts the closed end of the holder and the cannula end of theampoule. A gun spring drives a plunger which engages the ampoule todrive the ampoule and cannula forward causing the cannula to pierce theclosed end of the holder and to enter the locus which is to receive themedicament. During the movement of the ampoule, the helical spring iscompressed sufficiently to produce a counter force stopping the ampoule.The plunger continues to move forward pushing the piston in the ampouleto eject the medicament through the cannula. This continued movement ofthe plunger dissipates the energy of the gun spring and allows thehelical spring to overcome same and push the ampoule rearwardly thusretracting the cannula.

The counterbalancing effect provided by the helical spring is valuablein that if the cannula strikes a hard surface while being inserted, thisresistance coupled with the force of the compressed helical spring, willcause the cannula to stop entry and possibly retract depending on thedepth of penetration of the cannula which obviously will be a measure ofthe relativespring forces at any given position.

In view of the foregoing, it is an object of this inven tion to providea gun type hypodermic injection device having spring means tocounterbalance the gun spring power employed to insert the cannula andinject the medicament.

It is another object of this invention to provide a gun type hypodermicinjection device as above wherein the counter-balancing spring meansserves to retract the needle during injection to provide greaterdispersion of the medicament.

It is yet another object of this invention to provide a gun typehypodermicinjection device as above wherein the counter-balancingspringmeans serves as a shock absorber to control forward movement of theampoule under the force of the gun spring.

It is a still further object of this invention to provide a hypodermicinjection device wherein the counterbalancing spring serves to preventinjury to the user by employing the counter-balance spring force toassist in preventing further penetration of the cannula when it strikesa solid spot by providing an opposing force to counteract that of thegun spring.

IN THE DRAWINGS FIG. 1 is a cross-sectional view of the hypodermicinjection device of this invention as it is stored;

FIG. 2 is a cross-sectional view of the device after the gun spring hasforced the cannula out the closed end of the holder and has completedits outward travel;

FIG. 3 is a cross-sectional view similar to FIG. 1 illustrating a secondembodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION One form of this invention isillustrated in FIGS. 1 and 2 of the drawings. In this embodiment thedevice comprises an outer cylindrical sleeve having an intumed shoulderat one end and an annular groove 113 in the inner wall adjacent theother open end. A cartridge assembly 106 is assembled in the shoulderedend of the outer sleeve 100. The cartridge assembly 106 includes acartridge holder sleeve 104 fitted within the sleeve 100 and having adecreased forward end portion 153 forming a shoulder 154 which fitsagainst seat 112 provided by outer sleeve shoulder 110. The extremeforward end portion 156 of the holder sleeve 104 is tapered to form asmall circular opening which is closed by a cannula pierceable stopper158 that hermetically seals this end of the cartridge holder 104.

The cartridge includes an ampoule cylinder 136 with liquid medicament146 therewithin and a piston 148 at one end with a cannula 150 at theother end. The ampoule cylinder 136 has a necked portion 80 with adiameter less than that of the cylinder 136 and terminates in anenlarged annular flange. The cannula 150 is secured to a cannula sleeve82 which in turn is affixed to the enlarged flange in the necked portion80. More specifically, cannula sleeve 82 comprises a reduceddiameterportion 84 which is secured to the cannula 150 and an enlargedbody 86 forming a shoulder 88. The enlarged body .86 fits over and issecured to the annular flange on the necked portion 80 of the ampoulecylinder. Within the neck of the ampoule cylinder 136 between the innerend of the cannula 150 and the medicament there may be interposed afluid pressure rupturable diaphragm generally like that described in US.Pat. No. 3,391,695 to Sarnoff.

The cartridge assembly 106 is assembled in the outer sleeve 100 with thecannula 150 spaced from the stoppered end of the holder 104. The pistonend of the ampoule cylinder 136 is retained in place within the holdersleeve 104 by resilient contact between the exterior surface of theampoule 136 and an annular bead on the inner wall of the holder sleeve104 adjacent its open end. This bead 160 hermetically seals the ampoulecylinder at its piston end and frictionally retains it in positionwithin the holder sleeve 104. The diameter of the exterior of theampoule cylinder 136 is less than the internal diameter of the holdersleeve 104 throughout the majorlength of said holder sleeve so that oncethe ampoule cylinder is. moved forward and is free of the annular head160 and the cannula 150 has pierced the stopper 158, the ampoule 135will move freely in the holder sleeve. The gas in front of the ampoulewill readily flow therepast in the annular space between the ampoulecylinder and the inner wall of the holder sleeve 104 as the ampouletravels forward. By this method of sealing, the cannula 150 may bemaintained in a sterile environment until use is made of the device. Itshould be noted that the forward interior of the holder sleeve 104 iscontoured to form a seat 161. The overall length of the ampoule 135 andcannula 150 is such that it is all contained within the holder sleeve104 as illustrated in FIG. 1.

The outer sleeve 100 is of such length that it accommodates thecartridge assembly 106 in one end and receives the gun assembly 200 inthe other to complete the device. The gun assembly 200 comprises aninner gun sleeve 101 having an out turned flange 103 which fits upagainst the end of the cartridge holder sleeve 104 when the gun assemblyis inserted in the outer sleeve 100. The other end of the inner gunsleeve 101 is centrally apertured to form a hole 120. The rear outerface 122 of the inner gun sleeve 101 is planar and perpendicular to thelongitudinal axis of the sleeve for a purpose to be brought out later.

A plunger 162 fits within the out turned flange end of the inner gunsleeve 101. This plunger has a cylindrical body portion 163 and acircular head portion 164 of a diameter larger than the body portion 163and generally slightly less than that of the piston 148 in the ampoule135. The head 164 has an opening which is sized to align and correspondto the through-hole 166 in the plunger body 163. The plunger head 164 isprovided with a plurality of circumferentially spaced, radiallyextending tabs 168. These tabs 168 form a diameter greater than that ofthe plunger head 164 so that the tabs will engage the end of the ampoulecylinder 136. Longitudinal slots 172 are formed in the plunger head 164immediately behind the tabs 168. These slots are sized so that they willaccommodate the tabs 168 when they-are later broken off or bentrearwardly in the operation of the device. These slots extend throughoutthe length of the head behind the tabs.

' Referring to FIGS. 1 and 2, a locking detent 176 is fitted through thehole 166 in the plunger 162 and has a central body portion 178 withoutwardly extending lugs 180 on one end fitting on annular shoulder 182of the plunger head 164. The other end of the locking detent 176 isprovided with four equally spaced longitudinally extending springydetent arms terminating in frusto-conical detent heads 186. This lockingdetent 176 maintains the plunger 162 and inner gun sleeve 101 inassembled position with a coil spring 138 compressed therebetween asfollows. A coil spring 138 is positioned over the plunger body 163 andabuts the plunger head 164 at one end and the inner face of the end wallof the inner sleeve 101 at the other. Upon compressing of the coilspring 138 sufficiently the detent heads 186 will be cammed inwardly byengaging the periphery of the end wall opening 120 and pass therethroughwhereupon the bases of the detent heads 186 will come to rest on theplanar face 122 of the inner gun sleeve 101 to retain the plunger andinner gun sleeve in assembled condition with the coil spring 138compressed therebetween. When desired the rear planar surface 122 of theinner sleeve 101 may be overlaid with a metal washer 127, in which caseit is advantageous to provide a guide and holding flange 128 to surroundthe opening 120. The flange 128 is provided with a lip portion to retainthe washer in place.

As illustrated in FIGS. 1 and 2, the inner gun sleeve 101 has aplurality of longitudinally extending raised ribs 129 running from theflange 103 approximately one-half the length of the said sleeve. Anouter gun sleeve 192 fits over inner gun sleeve 101 and is sized tofrictionally engage ribs 129. The outer sleeve 192 has a closed end 194with a central aperture 196 from which extends a frusto-conical camsurface 198 sized and shaped to cooperate with frusto-conical detentheads 186 to cam said heads radially inwardly. The outer gun sleeve 192is provided with a circumferential locking rib 199 which fits in groove113 in the outer sleeve 102 to retain the gun assembly 200 in positionin said outer sleeve. It should be noted that the length of outer gunsleeve 192 is slightly less than that of the inner gun sleeve 101 so asto make certain that there will be space between the inner wall of theouter gun sleeve 192 and the flange 103 of the inner gun sleeve 101 sothat the two gun sleeves may move relative to each other to camfrusto-conical detent heads 186 inwardly in operating the device.

In order to make certain that the frusto-conical detent heads 186 arenot accidentally cammed inwardly, a safety pin assembly is provided.This safety pin assembly comprises a cap 142 having a cylindrical sleeve143 sized to fit over the end portion of outer gun sleeve 192. A safetypin 144 extends inwardly from the center of the cap 142 into the openingformed by the inner portions of the detent heads 186 to thereby preventinward movement of said detent heads. The cap 142 is provided internallywith a plurality of spacer abutments to assure proper positioning of thecap on the outer sleeve 192.

As illustrated in FIGS. 1 and 2 a spring means 210 is positioned withinthe cartridge holder 104 between ampoule cylinder 136 and the innerclosed end of the holder 104. More particularly, the spring means 210comprises a helical spring 212 positioned around cannula and interposedbetween the closed end of the holder 104 and flat end portion 214 of theampoule cylinder 136 surrounding the necked portion 80. It should benoted that a resilient washer 218 is positioned between the spring 212and the flat end portion 214 of the ampoule cylinder 136. The helicalspring 212 is sized to fit down into the reduced end portion 153 ofholder 104.

The embodiment illustrated in FIG. 3 of the drawings is similar to thatof FIG. 1 except for the helical spring arrangement. In this embodimentthe helical spring 212 surrounds the cannula 150 abutting againstshoulder 88 of the cannula sleeve 82 and the closed end of the holder104. The function is identical in both embodiments.

The function of the spring means 210 is threefold: namely, to act as ashock absorber, as a safety feature and as a means for retracting thecannula a small amount after complete projection thereof.

The device is delivered to the user in the form shown in FIG. 1. Foruse, initially the safety pin 144 is removed and then the forward end ofthe device is applied to the patient at the locus desired. Subsequently,when the outer gun sleeve 192 .is thrust toward the locus, a telescopingaction takes place between the outer and inner gun sleevesLAn advantageof the arrangement is that the outer sleeve 100 is long and theinjection device may be grasped very conveniently along substantiallyits entire length to operate it.

Telescoping action of the gun sleeves causes the frusto-conical camsurface 198 to cam the detent heads 186 together, whereby they becomesmaller in diameter than the opening 120, and the spring 138 becomeseffective to advance the plunger 162. In the initial movement, theplunger tabs 168 engage the end of the ampoule 136 and force itforwardly off the bead 160 and upon further travel forces the cannula150 through stopper into the position illustrated in FIG. 2. At thispoint, the ampoule cylinder 136 has substantially fully compressedspring 212 and cannula 150 fully introduced whereby further travel ofthe plunger 162 causes tabs 168 to be sheared off and fall back intoslots 172 so that the plunger may continue to move forward by engagingthe ampoule piston 148 to force the medicament out of the cannula 150.

It should be noted that the spring 212 is sized such that it will stoptravel of the ampoule 135 short of the holder shoulder 161 to therebyobviate any possibility of breaking of the ampoule by hard impactthereon. This is the shock absorbing feature of the spring previouslymentioned.

Additionally, the spring affords a safety feature as follows: Obviously,in the initial movement of the ampoule 135 under the force of gun spring138, this spring must have sufficient power to overcome spring 212.Balancing of these spring forces is a critical matter. Spring 1138 musthave enough stored energy to force the cannula 150 into the desiredposition and depth for introduction of the medication. On the otherhand, spring 212 upon compression by the ampoule 135 as it moves forwardmust build up sufficient resistance such that the movement of theampoule will stop short of the holder shoulder 161.

Obviously, as the ampoule moves toward the end of the holder 104, theforce of spring 138 diminishes and that being built up in spring 212increases. Thus a counterbalancing effect is achieved. Thiscounterbalance is important as a safety feature. For example, in the useof the device if the projecting cannula in its movement should strike asolid mass, the sudden impact coupled with the counter effect of thespring 212, will be sufficient to cause the cannula to stop and perhapsretract depending on the amount of projection that had taken place atthe specific instant of impact. This would avoid injury to the userwhich is a major consideration.

The third important feature of the spring 212 is the retraction of thecannula after it has been fully projected under the force of gun spring138. As set forth previously in describing the operation of the device,it will be recalled that the gun spring 138 drives the ampoule 135forward to force the cannula 150 out the end of the holder and into thelocus of application of the medicament. This complete forward movementof the cannula and ampoule is illustrated in FIG. 2 wherein the spring212 has been compressed to its maximum compression. At this point, thegun spring continues to push the plunger and engaged piston forward toforce the medicament out the cannula. As the plunger continues forwardto cause the piston to eject the medicament, the reduction in force ofspring 138 is overcome by spring 212 and the cannula 150 commences toretract slightly as the latter part of the ejection of the medicament istaking place. This retraction as the medicament is being injectedprovides good dispersion to decrease the time required for themedicament to take ef feet.

In view of the foregoing, it is now apparent that the hypodermicinjection device of this invention is a substantial step in theproducing of a foolproof and safe self-injection device having a widearea of use.

I claim:

1. In a hypodermic injection device comprising a gun, a cartridge holderhaving a closed end and in operative relationship to the gun, acartridge within the holder, said gun comprising a sleeve open at oneend thereof, a plunger positioned within the sleeve, spring power meansacting on said plunger tending to move it out the open end of thesleeve, restraining means cooperating with said plunger to preventplunger movement, safety means acting on said restraining means torender it inoperative, said cartridge holder comprising a hollow shellacting as a prolongation of the gun sleeve, a puncturable seal closingoff the end of the holder remote from the gun, said cartridge includingan ampoule comprising a hollow cylindrical sleeve, a piston slidablypositioned in one end thereof and means mounting a can nula extendingfrom and closing off the other end, a fluid within the cylindricalsleeve between the piston and the cannula, the cartridge fitting withinthe cartridge holder with the free end of the cannula within the closedend of the holder, the improvement comprismg:

shock absorbing and retracting spring means interposed between thecannula end'of the cartridge and the closed end of the cartridge holder,said shock absorbing and retracting spring means being sized whereby itis compressed by the cartridge and acts as a shock absorber as saidcartridge moves under the force of the spring power means until thecannula is fully projected into the patient, the shock absorbing andretracting spring means being further characterized by having acompressed spring force when the cannula is fully projected into thepatient and injection begins under the continuing expansion of thespring power means .to overcome the force of the spring power means andretract the cannula while injection continues and is completed.

2. The invention as set forth in claim 1 and wherein the shock absorbingand retracting means comprises a coiled spring positioned around thecannula between the cannula end of the cartridge and the closed end ofthe cartridge holder.

3. The invention as set forth in claim 2 and wherein the coiled springis a helical spring.

4. The invention as set forth in claim 1 and wherein the hollowcylindrical ampoule sleeve is necked down at its cannula end to form acylindrical projection of reduced diameter, an annular flange formed onthe end of said projection, and a cannula sleeve connected to thecannula and fitting over the flange to secure the cannula to the ampouleand further wherein the shock absorbing and retracting spring meanscomprises a helical spring fitting around the cannula and abutting thatportion of the ampoule cylinder around the cylindrical portion ofreduced diameter and the closed end of the cartridge holder.

5. The invention as set forth in claim 1 and wherein the hollowcylindrical ampoule sleeve is necked down at its cannula end to form acylindrical projection of reduced diameter, an annular flange formed onthe end of said projection, and a cannula sleeve connected to thecannula, said cannula sleeve having a portion secured to the cannula andan enlarged portion fitting over and secured to the flange and furtherwherein the shock absorbing and retracting spring means comprises ahelical spring fitting around the cannula and abutting the enlargedportion of the cannula sleeve and the closed end of the cartridgeholder.

6. The invention as set forth in claim 4 and wherein a resilient washeris positioned between the helical spring and the ampoule cylinder.

* a a air

1. In a hypodermic injection device comprising a gun, a cartridge holderhaving a closed end and in operative relationship to the gun, acartridge within the holder, said gun comprising a sleeve open at oneend thereof, a plunger positioned within the sleeve, spring power meansacting on said plunger tending to move it out the open end of thesleeve, restraining means cooperating with said plunger to preventplunger movement, safety means acting on said restraining means torender it inoperative, said cartridge holder comprising a hollow shellacting as a prolongation of the gun sleeve, a puncturable seal closingoff the end of the holder remote from the gun, said cartridge includingan ampoule comprising a hollow cylindrical sleeve, a piston slidablypositioned in one end thereof and means mounting a cannula extendingfrom and closing off the other end, a fluid within the cylindricalsleeve between the piston and the cannula, the cartridge fitting withinthe cartridge holder with the free end of the cannula within the closedend of the holder, the improvement comprising: shock absorbing andretracting spring means interposed between the cannula end of thecartridge and the closed end of the cartridge holder, said shockabsorbing and retracting spring means being sized whereby it iscompressed by the cartridge and acts as a shock absorber as saidcartridge moves under the force of the spring power means until thecannula is fully projected into the patient, the shock absorbing andretracting spring means being further characterized by having acompressed spring force when the cannula is fully projected into thepatient and injection begins under the continuing expansion of thespring power means to overcome the force of the spring power means andretract the cannula while injection continues and is completed.
 2. Theinvention as set forth in claim 1 and wherein the shock absorbing andretracting means comprises a coiled spring positioned around the cannulabetween the cannula end of the cartridge and the closed end of thecartridge holder.
 3. The invention as set forth in claim 2 and whereinthe coiled spring is a helical spring.
 4. The invention as set forth inclaim 1 and wherein the hollow cylindrical ampoule sleeve is necked downat its cannula end to form a cylindrical projection of reduced diameter,an annular flange formed on the end of said projection, and a cannulasleeve connected to the cannula and fitting over the flange to securethe cannula to the ampoule and further wherein the shock absorbing andretracting spring means comprises a helical spring fitting around thecannula and abutting that portion of the ampoule cylinder around thecylindrical portion of reduced diameter and the closed end of thecartridge holder.
 5. The invention as set forth in claim 1 and whereinthe hollow cylindrical ampoule sleeve is necked down at its cannula endto form a cylindrical projection of reduced diameter, an annular flangeformed on the end of said projection, and a cannula sleeve connected tothe cannula, said cannula sleeve having a portion secured to the cannulaand an enlarged portion fitting over and secured to the flange andfurther wherein the shock absorbing and retracting spring meanscomprises a helical spring fitting around the cannula and abutting theenlarged portion of the cannula sleeve and the closed end of thecartridge holder.
 6. The invention as set forth in claim 4 and wherein aresilient washer is positioned between the helical spring and theampoule cylinder.